A hard-disk drive (HDD) is a non-volatile storage device that is housed in a protective enclosure and stores digitally encoded data on one or more circular disks having magnetic surfaces (a disk may also be referred to as a platter). When an HDD is in operation, each magnetic-recording disk is rapidly rotated by a spindle system. Data is read from and written to a magnetic-recording disk using a read/write head which is positioned over a specific location of a disk by an actuator.
A read/write head uses a magnetic field to read data from and write data to the surface of a magnetic-recording disk. As a magnetic dipole field decreases rapidly with distance from a magnetic pole, the distance between a read/write head and the surface of a magnetic-recording disk must be tightly controlled. An actuator relies on suspension's force on the read/write head to provide the proper distance between the read/write head and the surface of the magnetic-recording disk while the magnetic-recording disk rotates. A read/write head therefore is said to “fly” over the surface of the magnetic-recording disk. When the magnetic-recording disk stops spinning, a read/write head must either “land” or be pulled away onto a mechanical landing ramp from the disk surface.
The performance capabilities of a read/write head can vary significantly from head to head. This is so because several hundred or more processes may be involved in the manufacturing process of a head, which results in manufactured heads having a wide distribution of physical and performance characteristics. As performance of a head increases, the width of the track to which the head can write decreases. Thus, better performing heads can be used with narrower tracks.
Two common types of digital storage media are discrete track media (DTM) and continuous media. In discrete track media (DTM), tracks are pre-patterned with magnetic tracks (lands) separated by non-magnetic grooves. On the other hand, in continuous media, tracks are not pre-patterned and the surface of the disk does not contain any non-magnetic grooves.
When continuous media is used, the track format may be adapted during operation to reflect the particular performance characteristics (such as the signal to noise ratio) of the particular head used in the HDD. However, in discrete track media, tracks are pre-patterned on the magnetic-recording disk and the area between each track is constructed to be non-magnetic. Consequently, in discrete track media (DTM), the ability to customize the track format during operation is lost.
To accommodate the wide distribution of performance characteristics across read/write heads, multiple templates may be designed for a DTM magnetic-recording disk. Each template specifies a different design for physically laying out tracks on the disk. For example, different templates may specify different track pitches. When manufacturing a particular HDD employing a DTM disk, the performance capabilities of the actual head to be used in the HDD are evaluated. Once the performance capabilities of the head are known, the template having a track format that is best suited for the particular head being used in the HDD may be selected. After selecting the template that is best suited for the actual head to be used, the magnetic-recording disk may be pre-patterned with tracks according to the selected template.